On Tue, 04 May 1999 12:52:19 -0500, Joel Wilcox wrote:
>At 10:29 AM 5/4/99 -0500, you wrote:
>>Could someone, in plain english, explain to me the significance of F
>>Stop once you're focused at infinity. For instance, if I'm shooting
>>the horizon (focused at infinity), what difference does the F stop
>>make beyond the obvious relationship to shutter speed?
>>
>>BBB
>
>I don't speak plain English, but that never stops me. <g> It doesn't
>matter what f stop you choose if you are focused on infinity and infinity
>is what you want in focus, unless one stop on your lens happens to be
>sharper than another.
Given that I can't actually see infinity (poor eyesight, you know),
what I typically want in focus on these shots is the barn a half mile
away and on the horizon, or the clouds, or some other object that is
too far away to focus on anything other than infinity. The 35-70
3.5-4.5, for example, only focuses practically to 10 yards or so - so
an object at 50 feet ends up focused at infinity, or so close that
the difference is negligible.
So what I'm wondering is what will happen if I shoot the barn on the
horizon (say, 1/2 mile) with the 200/5 at f5, f16, and f32, assuming
I use the appropriate shutter speed?
>But I can think of only one instance in which I deliberately focused on
>infinity. I was shooting a 200mm + 2X TC shot of a sunset over water,
>couldn't focus with this combination anyway, and said to myself if I focus
>on infinity at least the sun will be as sharp as possible. Ordinarily I'm
>trying to maximize depth of field from some uncertain point in the
>foreground to infinity, and I use the depth of field markings on the lens
>barrel to make sure that the infinity mark is within the mark of the stop I
>plan to use. The smaller the stop, the greater this depth of field.
>
>Have I understood your question?
Yes you have, thanks.
BBB
-
B.B. Bean - Have horn, will travel
bbbean@xxxxxxxxxxxxxx
Peach Orchard, MO
http://www.beancotton.com/bbbean.shtml
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